Zevachim 4 - September 18, 25 Elul

What is the source for the Mishna's ruling that if one intends a different sacrifice than the one designated, the offering is no longer valid to fulfill the obligation of the original owner? The Gemara investigates the derivation of this principle across each of the four sacrificial rites: slaughtering, collecting the blood, carrying the blood to the altar, and sprinkling the blood on the altar. Why is it not sufficient to derive the law from just one of these rites? The Gemara then poses a similar question regarding a change in ownership—specifically, if the sacrifice was offered on behalf of someone other than its designated owner. Again, it seeks a source for each of the four rites. If these requirements are mandated by Torah law, why do they not render the sacrifice invalid?